Description:
This perennial wildflower is an emergent aquatic that produces leaves
and flowers directly from underwater rhizomes. The leaf blades are
1-2½' across; they are orbicular and concave toward their centers,
smooth
and slightly wavy-drooping along their margins, and peltate (each
petiole
joining its leaf blade near the middle). The upper blade surface is
light to dark green and glabrous, while the lower blade surface is
light green and slightly hairy. Several veins radiate from the center
of each leaf blade, branching dichotomously toward its margin. The
relatively stout petioles are 2-6' long, light green, terete, and
glabrous; they contain internal chambers of air. Most leaf blades are
held about ½-3' above the surface of the water on their petioles,
although a minority of leaf blades may float on the surface of
the water.

Flowers are produced individually from stout peduncles about 3-6' tall.
The peduncles are light green, terete, and glabrous; like the
petioles, they also contain internal chambers of air. The flowers are
held about ½-3' above the surface of the water. Each flower is about
4-8" across, consisting of 10-20 tepals, an obconic receptacle, and
numerous stamens. The outermost tepals are light green, otherwise they
are white to pale yellow. The golden yellow stamens have hooked
appendages at their apices. Each receptacle has 10-20 pistils
along its truncate upper surface that are embedded in pits. The
blooming period occurs during mid- to late summer for about 1½ months.
Individual flowers are short-lived and often mildly fragrant.
Afterwards, the receptacles of the flowers become 3-6" across and turn
brown; each receptacle contains 10-20 nut-like seeds. Individual seeds
are about ½" across and ovoid-globoid in shape; the receptacle
eventually bends downward to release the seeds into the water. The root
system is long-rhizomatous. Rhizomes that are produced during late
summer and fall become swollen and starchy. This wildflower is a strong
colonizer.

Cultivation:
The preference is full sun, shallow
water about 1-4' deep, and a soil bottom that is mucky or sandy. Bodies
of water with strong waves or fast-flowing currents should be avoided.
This wildflower can spread aggressively and eventually dominate a
shallow pond by overshading other aquatic plants. The
hard-coated seeds can remain viable for several decades.

Range
& Habitat: The native American Lotus is occasional
in southern and
western central Illinois, while in the rest of the state it is
uncommon. It is possible that Amerindians introduced this
wildflower into new areas prior to the time of European settlement as
its starchy rhizomes and seeds were used by them as sources of
food. Habitats include ponds, quiet inlets of lakes, marshes with
open water, margins of slow-moving rivers, sinkholes, and open shallow
water in front of dams. Large colonies of American Lotus occur along
the Illinois River.

Faunal
Associations: The flowers are cross-pollinated by
honeybees, Halictid
bees (Halictus spp.,
Lasioglossum spp.),
and masked bees (Hylaeus
spp.), which collect pollen for their larvae. The
following bee species are oligoleges
of American Lotus: Lasioglossum
nelumbonis, Lasioglossum
nymphaearum,
and Hylaeus nelumbonis.
Other visitors include flower flies
(Syrphidae), shore flies (Ephydridae), and miscellaneous beetles. This
latter group of floral visitors feed on pollen. The caterpillars of two
moths, Bellura obliqua
(Cattail Borer Moth) and Ostrinia
penitalis
(American Lotus Borer), mine the foliage or bore through the rhizomes
of
American Lotus. The seeds of this wildflower are consumed by the Canada
Goose, Mallard, Northern Shoveler, and probably other waterfowl.
Muskrats sometimes feed on the rhizomes, peduncles, and petioles.

Photographic
Location: A shallow marshy lake at the Heron Boardwalk in
Vermilion County, Illinois.

Comments:
American Lotus is perhaps the grandest and most imposing native
wildflower of wetland
areas in Illinois. It resembles such emergent aquatics as Nuphar advena
(Spatterdock) and Nymphaea
odorata (Fragrant Water Lily), but its
leaves are held well-above the surface of the water and its flowers
have distinctive obconic receptacles. An introduced species, Nelumbo
nucifera (Sacred Lotus), is occasionally cultivated in
ponds and pools
of water, but it has not naturalized in Illinois thus far. It can be
distinguished from American Lotus by its pink flowers (rarely white)
and petioles that are occasionally prickly.